Arsenal fought back from 2-0 down to beat fierce north London rival Tottenham 5-2 in the Premier League on Sunday and boost its chances of qualifying for the Champions League for a 15th straight season.
Spurs led in the fourth minute through Louis Saha and former Arsenal striker Emmanuel Adebayor made it 2-0 with a penalty. But Bacary Sagna and Robin van Persie brought the scores level before halftime and Tomas Rosicky put the Gunners ahead six minutes into the second half.
Theo Walcott then scored twice to give Arsenal its biggest derby win over Tottenham since a 5-0 win at White Hart Lane in December 1978.
The Gunners moved to within seven points of third-place Tottenham and kept fourth place from Chelsea on goals scored.
"Arsenal is alive more than anyone thought before the game," Arsenal manager Arsene Wenger said. "Our spirit, our drive, our style - everything was perfect.
"At 2-0 down, we just refused to lose the game. At 2-2, you could see that if we maintained the pace we would win the game."
In a season in which it has lost to Blackburn and Swansea - and been beaten 8-2 at Manchester United - Arsenal has now scored five goals against each of its biggest London rivals. Arsenal beat Chelsea 5-3 at Stamford Bridge in October.
Shrugging off the inconsistent form that has bedeviled it this season, Arsenal played at the sort of pace more commonly associated with Tottenham this season and troubled its opponents throughout.
Tottenham's misery was completed with three minutes remaining when Scott Parker was sent off for a second yellow card following a late challenge on Thomas Vermaelen. The midfielder will now be suspended for next weekend's match against Manchester United.
Ten points behind Premier League leader Manchester City with 12 games remaining, Tottenham's unlikely challenge for a first league title since 1961 appears to be over.
Arsenal's midfield of Rosicky, Alex Song and the on-loan Yossi Benayoun dominated the match, taking advantage of the space created by visiting manager Harry Redknapp's decision to start with both Saha and Adebayor up front.
"We were getting overrun," Redknapp said. "They were bossing the game."
Sagna headed in unmarked from Benayoun's cross, Van Persie struck a curling shot from outside the area, Rosicky flicked in from a flowing team move and Walcott twice surged clear to round off counterattacks.
Only a deflection for Saha's opener and a contentious penalty when Gareth Bale tumbled over diving goalkeeper Wojciech Szczesny gave Tottenham its two-goal lead.
"I felt we were a bit nervous at the start and, when we got slowly back to more calmness, our two center backs became outstanding," Wenger said. "The first goal we got caught on a counterattack and the second was not a penalty."
Arsenal had been widely criticized by fans and commentators this season for a lack of spirit but the Emirates Stadium crowd was roused to celebration and joyful chanting rather than the apathy and even vitriol that have been more common this season.
Chasing a first home-and-away double over Arsenal since the 1992-93 season, Tottenham led from the first clear opening.
Saha ran completely unmarked up the middle of the field onto a pass by Adebayor. Selected ahead of Rafael van der Vaart, Saha took the ball into the box and fired in a hopeful low shot that deflected off defender Vermaelen's legs and looped over Szczesny into the net.
The Gunners responded with vigor, Kieran Gibbs tumbling over Kyle Walker's leg in the area, Walcott drawing an interception in the area from Ledley King and Van Persie forcing Younes Kaboul into a sliding block in the space of several hectic minutes.
Van Persie shot wide of the left post and had another effort deflected past the right before Friedel made a point-blank one-handed save to push Rosicky's header from a corner over the bar.
Van Persie hit the post in the 40th but Tottenham's reprieve was temporary as the ball came back in from the left and Sagna powered a header from about 12 meters (yards) past the diving Friedel.
It was 2-2 three minutes later as Tottenham failed to clear the ball and Van Persie curled an unstoppable left-foot shot from the edge of the area around his marker and past Friedel's full-stretch dive.
Arsenal almost led within two minutes of the restart but Friedel got his fingertips to Benayoun's shot along the ground to touch it past his post.
Again, the reprieve was short lived. Rosicky lifted the ball over Friedel after neat interplay with Sagna, Walcott held off Walker to smash in a 65th-minute fourth after a lofted pass by Van Persie and the England winger hit the fifth goal three minutes later from a long pass by Song.
Although it is still in the FA Cup, Tottenham's focus is now on sustaining its challenge for third place and an automatic Champions League qualifying spot.
"It's going to be tight but we're still in a great position," Redknapp said. "If we can make third spot, that will be a great season for us."